Couplings or adapters for optical-fiber plugs connect optical fibers for laser light. Couplings of this type are usually fixed in a housing wall or front panel, with the result that plug receptacles for optical-fiber plugs are provided on both sides of the front panel. Until recently, optical-fiber connectors of this type were frequently produced in the form of SC plugs or SC connectors.
However, these are increasingly being replaced by smaller forms with the designations LX.5, LC and MU (Internet advertisement on Aug. 6, 2001 at 15.25 under the address http://www.bicsi.org/prico8/sld001.htmsld035.htm).
LC connectors are standardized in IEC 61751-20 and MU connectors are standardized in IEC 61751-6. LX.5 plugs have not yet been standardized; LX.5 is a registered trademark of the company ADC Telecommunications, Inc., US; plugs of this type have improved properties (Internet presentation on Aug. 6, 2001 at 15.28 under http://stele.adc.com/Library/Literature/1236.pdf).
SC connectors and corresponding couplings are disclosed in U.S. Pat. No. 5,317,663. The plug-in connectors are held in the coupling on both sides by blocking cams which engage in depressions on both sides of the connector when the optical-fiber centering devices have reached their desired position. The adapters there, for SC-simplex connectors, are provided with shutters against laser light, arranged in the coupling.
A coupling of the type “BSC II-Adapter with Shutter,” for a SC connector, could be seen on the Internet on Aug. 6, 2001 at 15.35 under the address http://www.molex.com. A shutter is understood as meaning a pivotally attached flap in front of a plug-receptacle opening which is intended to prevent a fitter from being injured by laser light during the insertion of SC connectors. The shutter has a warning about lasers.
EP 0 590 586 A1 discloses a coupling made up of two parts for two MU connectors, a reduced-size further development of the SC connector which can be fastened on a front panel by means of flanges projecting from one side of the coupling, with a springing-back spring next to the flange arresting the coupling behind the front panel after it has been pushed into a corresponding opening. The plug-in connector is held in the coupling in a way similar to the SC connector.
WO 00/16145 discloses fiberoptic connectors and couplings of the type described. Smaller forms of connector of the LX.5 type are presented, having at the front of the connector a cover which automatically opens as soon as a laser shutter against a return spring, arranged in the coupling, has been passed. During the insertion phase, a pin on the plug-in connector, protruding fixedly into the interior of the coupling, pushes open the cover held closed by a spring, in order that the optical fiber in the plug-in connector is exposed for conducting light to a plug-in connector lying opposite in the adapter. The connector engages with its two special cams on a resilient lever on the housing of the plug-in connector in a complimentarily shaped catch on the coupling, which are arranged laterally of the longitudinal axis of the connector and of the coupling, respectively, and thereby hook into one another. The cams can be unlocked from their catch by means of the lever on the connector.
LC connectors are also known from EP 1091226 A1. They have a locking and releasing lever mechanism arranged centrally on one side of the connector, by which a positive connection produced in the coupling when the connector is inserted can be released. The connection is produced by two keys arranged laterally on the lever, which engage in a keyway lying opposite in the coupling when the connector has reached its desired position in the coupling. These couplings also have flanges and a latching spring for mounting in a front panel.
Instead of a large-sized SC coupling, it is possible to fit two couplings for LX.5, LC or MU connectors into a front panel. Although some of the plug-in connectors are standardized, on different systems of different users there are different plug-in connectors which come together but do not fit into the same coupling.
On Aug. 17, 2001, a universal adapter system for the plug-in connectors of the FC, ST, SC, SMA, 04 and BICONIC types could be seen under the Internet address http://www.fiberplus.com/cpakit.htm and a Universal Panel Mount Adapter, with which the ST or FC types can be coupled at a front panel to each other or to DIN or E2000 plug-in connectors, was advertised under the address http://www.fiberplus.com/upa.htm. An adapter for the coupling of MU types to LC types by simple mechanical screwing of slip-on ferrules for optical fibers with threaded rings is also provided. The fitting and removal of the adapters is time-consuming and requires great dexterity, in particular in the case of the small plug-in connectors, the ferrules of which have diameters of only 1.25 mm, as compared with 2.5 mm in the case of the SC connectors.
On Aug. 6, 2001 at 15.30, along with LC plugs and MU plugs with matching adapters for a simplex or duplex application, also presented on the Internet under the address http://www.senko.com/senkoadv/ was a SC-LC adapter device, which can be attached to a front panel and has at the front a plug receptacle for a LC plug and at the rear a plug receptacle for a SC plug. This coupling cannot be released, or only laboriously, from the front side once it has been fitted into the front panel from the front side and hooked behind the front panel by means of an expanding spring. This type of fastening is predominantly encountered in the case of all couplings that are not screwed on.
For this reason, the invention is based on the problem of providing an adapter which has the advantages of the known plug-in connectors and couplings but avoids their disadvantages.